Exploring Nuclear Fuels at High Pressure and Temperature: From Cradle to Grave

Actinide materials are of great importance due to their wide-ranging uses in modern industry. For example, uranium dioxide (UO₂) is used as the primary nuclear fuel in light-water reactors (LWRs). However, nuclear reactor accidents such as the Fukushima disaster in 2011 have encouraged the nuclear energy industry to explore alternative accident-tolerant nuclear fuels (ATNFs) such as uranium-silicide (U-Si) compounds. A number of U-Si phases (e.g., U₃Si₂, U₃Si₅) possess higher thermal conductivities than the conventional UO₂ fuel under nuclear reactor operating conditions. Higher thermal conductivities allow better heat dissipation in ATNFs when used in reactors. Nonetheless, significant research is needed to understand their structural stability and physical properties (e.g., mechanical properties) under both ambient conditions and those of elevated pressures and temperatures. An important elastic property significant to ATNF mechanical integrity is compress-ibility (i.e., inverse of bulk modulus). A powerful tool to study mechanical properties is applied pressure due to its ability to change structural characteristics. By applying pressure in concert with X-ray diffraction (XRD) technique, structural behavior and mechanical strength can be examined.

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